| 摘要 |
<p>The process consists of (a) washing the glass sheet with two catalysts applied separately; (b) treating it by application of the metal reserve formula, which produces a ppte. of lead on the glass; (c) covering with Judea bitumen; (d) etching the lead sheet with hydrofluoric acid, giving rise to lines of up to 1/2 mm thickness and protecting those parts not to be engraved with any paint resistant to hydrofluoric acid.</p> |
